This invention relates to a driving apparatus for a powder compacting press which transmits a vertical movement force to an upper ram for powder compacting.
Heretofore, a driving apparatus for a powder compacting press was adapted to rotate a power shaft by inertia rotation of a fly wheel through a motor, transmit this rotation to a crank shaft reducing it with a reduction gear consisting of gear rows, transmit the rotation of the crank shaft to the upper ram via a connecting rod and perform a press operation by moving the ram vertically. The purpose of the compression process in powder compacting is generally to promote the "compactibility" between powder particles at a nearly completed time of compression together with compacting which accompanies the air removal between powder paticles and plastic deformation. When the vertical movement of the upper ram with respect to one rotation of the crank shaft in a transmission system of driving force is plotted to a timing diagram, it is shown by a sine curve as shown in a dot-dash-line B of FIG. 3 and since the powder feeding time is comparatively long, sufficient powder feeding is possible.
However, since the lower dead point of the upper ram in this driving force transmission system is instantaneous (in a second) and short in time for compacting, the "compactibility" between powder particles is poor and spring back is large. Accordingly, these problems require the necessity of a large pressing force and easy occurrence of lamination for a forming product compared with compacting wherein a toggle curve is drawn.
Against this driving force transmission system, a driving apparatus, wherein an upper ram is actuated along a curve shown in broken line C of FIG. 3, using a toggle link mechanism, is also developed. Such toggle link mechanism, however, is short in powder feeding time and its feeding is also insufficient. Further, it is not only difficult in speed up, but also complicated mechanically.